1. Technical Field
This invention is concerned with a disc brake, eg for the wheel of a vehicle.
2. Related Art
In WO 98/25804, there is disclosed a disc brake which comprises two discs mounted on the same hub to rotate with the hub about a central axis of the hub, and friction material pads arranged on opposite sides of both discs including two pads between the discs. The discs are slidable axially on the hub and the pads are slidable in a parallel direction except for one pad which is fixed relative to the hub. Said disc brake also comprises an operating mechanism operable to bring the pads into contact with the discs to apply a braking force thereto. The brake also comprises a slideway on which at least one of said pads is supported for sliding movement towards or away from the disc. The slideway comprises a guidance member on which the movable pads are slidably-supported, ie the guidance member provides a slideway on which pads are supported for movement towards or away from said discs. The operating mechanism, which comprises a hydraulically-operated piston and cylinder assembly, the cylinder of which is fixed on a suspension link. The operating mechanism operates to move a first of the pads on the slideway into contact with a first of the discs, causing movement of the first disc on the hub to bring the other pad associated with that disc into contact with the first disc. The movement continues moving the pads which are between the discs so that one of them contacts the second disc which moves into contact with the other pad associated with the second disc which is the pad which is fixed relative to the hub. The guidance member is supported by bolts which pass therethough and fix it to said cylinder. As further explained in WO 98/26191, the bolts enable the bending and shearing forces applied to the pads during operation of the brake to be taken by the bolts while the guidance member itself can be made from lower strength material. The slideway is relatively complex to assemble and requires relatively long holes to be drilled through the guidance member to receive said bolts.
It is an object of the present invention to provide a disc brake having a simplified slideway which is easier to assemble.
The invention provides a disc brake comprising a disc, friction material pads arranged on opposite sides of the disc, and an operating mechanism operable to bring the pads into contact with the disc so that the pads apply a braking force to the disc, the brake also comprising a slideway on which at least one of said pads is supported for sliding movement towards or away from the disc, characterised in that said slideway is formed by a guidance member which defines at least two parallel grooves in a surface of the guidance member, the grooves extending parallel to the direction of the slideway, the guidance member being supported by parallel rods which are received in said grooves.
In a disc brake according to the invention, the grooves in the guidance member are much easier to form than long holes through the guidance member and, in assembling the brake, the guidance member can simply be fitted over the rods.
A disc brake according to the invention may be of the type disclosed in WO 98/25804. That brake comprises two discs which are slidable on the same hub under the control of leaf springs which act between the hub and the discs. The brake also comprises a cylinder which is integrally formed with a suspension link and a caliper also fixed to the suspension link, the caliper having supports for friction material pads mounted thereon.
Preferably, in a disc brake according to the invention said guidance member defines a protuberance between said grooves, the protuberance being a close fit between two of the rods.
The rods are, preferably, provided by bolts.
The guidance member may be made of plastics material or metal such as aluminium. Preferably, the guidance member is formed as an extrusion, since the guidance member can be formed with a constant transverse cross-sectional shape.